The present invention relates to an active matrix liquid crystal display device which includes wiring lines arranged in a matrix, and pixel electrodes disposed in regions surrounded by the wiring lines and connected to the pixel electrodes through switching elements.
In general, an active matrix liquid crystal display device of a light transmission type has an array substrate, an opposite substrate, and a liquid crystal composition held between the array substrate and the opposite substrate.
The array substrate has the following structure: a plurality of signal lines and a plurality of gate lines are arranged on a glass substrate in a matrix manner, and thin film transistors (hereinafter referred to as TFTs) are provided at the intersections of the signal lines and gate lines. Pixel electrodes formed of Indium Tine Oxide (hereinafter referred to as ITO) are arranged in regions surrounded by the signal lines and gate lines, and connected to the signal gate lines through switching elements, respectively.
On the other hand, the opposite substrate has the following structure: a black matrix pattern formed of light-shielding material such as Cr is formed on a glass substrate, and red (R), green (G), and blue (B) colored layers are formed as color filters on the black matrix pattern. Furthermore, an opposite electrode formed of a transparent conductive film of, e.g., ITO is formed on the colored filters.
The array substrate and opposite substrate are adhered to each other with a predetermined gap, and a liquid crystal composition is sealed in the gap between the array and opposite substrates, thereby forming the liquid crystal display device. In addition, spacers are arranged between the array and opposite substrates in order to keep those substrates apart from each other by the predetermined gap.
In recent years, liquid crystal display devices have been provided which use pillar-shaped spacers, instead of spherical spacers. More specifically, in these display devices, the opposite substrate has a plurality of pillar-shaped spacers projecting toward the array substrate, and distal ends of the spacers are located to contact the wiring lines of the array substrate, e.g., the gate lines, thereby keeping the gap between the array and opposite substrates, i.e., a cell gap, at a predetermined value.
Each of the pillar-shaped spacers is formed of colored layers which have successively been stacked. On the spacers, the opposite electrode formed of ITO are arranged.
By virtue of the above structure, the pillar-shaped spacers can be selectively arranged on the gate lines which are non-display regions. The spherical spacers cannot be arranged in such a manner. In this regard, the liquid crystal display device using the pillar-shaped spacers is more advantageous than the liquid crystal display device using the spherical spacers.
However, in the above liquid crystal display device using the pillar-shaped spacers, when an external force is applied to the liquid crystal display device and the array and opposite substrates are displaced from each other, the spacers are greatly moved relative to the array substrate. In particular, this is remarkable in recent liquid crystal display devices in which the array and opposite substrates are formed of thinner transparent substrates in order for the devices to have smaller weights. Those devices themselves have lower strengths, and are easily deformed due to external impact. When the spacers are moved relative to the array substrate, the opposite electrode covering the spacers is brought into contact with the pixel electrodes of the array substrate, causing a short-circuit and generating luminance spots.